Easy-open can ends of aluminum base alloys have been perfected and marketed over the years with the constant objective of obtaining high quality at minimum cost. Testing of ends to maintain their quality is essential.
The ideal test is to seam an end on a can body and inject air under pressure into the can until the end fails, either through rupture along the scoring necessary for easy opening, or by buckling of unscored portions of the end. This has become the conventional test, in spite of the trouble and expense of performing it. Unfortunately, testing an end by itself has involved mechanical clamping to hold it in place and in sealed relation to the test equipment, and the test results in that case do not correlate reliably with results of testing while seamed on a can body. The result is that testing is not regularly done at the end of each production line and this has inhibited further progress in reducing the amount of metal in ends, which is a significant factor in their cost.